Safari tour guide David Webb (Robert Powell) takes a job as head of security on the luxury train Pride of Africa and discovers that the wealthy passengers can be just as dangerous as the wild animals he knows so well. As the train sets off across the lush countryside, Webb contends with a dangerous kidnapping plot, a heated lovers' quarrel and a possible murder in this made-for-TV mystery set in the 1930s.

Chocky hopes, with Matthew and Albertine's help, to help the human race discover cosmic power, which unlike Earth's finite natural resources, will sustain them for as long as the universe itself exists. But their knowledge has aroused a great deal of interest from the military, and they are willing to take drastic action if they don't get what they want.

Matthew Gore is an intelligent boy chosen by a mysterious extraterrestrial visitor to be a source of information about life on Earth. As his schoolwork and artistic talent improve dramatically he arouses the suspicion of powerful groups who wish to tap into the amazing fund of knowledge to which he is now party.

A year has passed since Matthew said goodbye to his alien friend, and in the summer holidays he meets Albertine, a mathematical prodigy, with whom he discovers he can communicate telepathically. One day Chocky returns to warn Matthew that they are both in danger. When he returns to tell Albertine, he finds she has disappeared.

A once harmonious pair of angelic youth are disrupted when one decides he is fed up with his simple way of life. He takes a drastic step in order to get closer to the human boys he envies.